Improvement in slide-valves for



' `UNITED STATES PATENT Prion.

WILLIAM B. ROBINSON, OF DETROIT, MICHIGAN.

IMPROVEMENT IN SLIDE-VALVESFOR. STEAM-ENGINES.

-Speclcation forming part of Letters Patent No. 39,955, dated September15, 1863.

T0 all whom it may concern:

, Be it known that I, WILLIAM B. RoniNsoN, of Detroit, in the county ofWayne and State ot' Michigan, have invented a new and useful improvementin means of relieving the slide- Valves of steam-engines of unnecessarypressure; and I do hereby declare that the following is a full, clear,and exact description of the same, reference being had to theaccompanying drawings, forming part of this speciiication, in which-Figure l is a longitudinal vertical section or" the slide-valve and seatand part of the steam-chest cover of a horizontal engine, illustr-atingthe application of my invention. Fig. 2 is a plan ofthe valve.

Similar letters of reference indicate correspending parts in bothfigures.

This invention relates to the protection of the back of the valve fromthe pressure of the steam in the steam-chest by means of a packing,which is fitted to the valve and works in contact with the inner face ofthe cover of the chest.

It consists in novel construction and arrangement ofthe packing, wherebythe pressure ofthe steam is made to keep it steam-tight and compensatefor wear.

To enable others skilled in the art to make and use my invention, I willproceed to describe its construction and operation.

A is the valve, a a the seat, and B the steam-chest cover, the innersurface of which is faced flat and parallel with the valveseat. The faceof the valve may be of ordinary form and the ports b b c in the seatarranged in the usual manner.

The valve is constructed with a circular ange, d, around its back andwith an annular projection, d', on the said lian ge, extending nearly tothe inner face of the cover B, and in this projection there is formed anannular cavity, e', for the reception of two packing-rings, f and g, thetransverse section ot the said cavity being of square form. The outerpackingring, f, is of angular t'orm in its transverse section, or, inother words, 'has a rabbet formed in the upper part of its interior,that it may receive within it the inner ring, g, the

transverse sectional form ot' which is quadrangular and of sufcient sizeto ill the rabbet in the outer ring, so that both rings may fit thecavity e. At suitable distances apart there are a number of holesprovided in the bottom of the cavity e for the reception ot' spiralsprings h h, which serve to press against the bottom ofthe outer ringand so keep the two rings in contact with the at interior surface ot'the cover B when there is no steam in the chest. The rings are each cuttransversely at one or more points, as shown at t' z' in Fig. 2, orformed in segments to enable the outer one to contract upon the innerone and the inner one to contract closely upon the inner face of thecavity e, and holes jj are provided in the exterior of the tia-nge,communicating with recesses 7c k in the cavity e, to admit steam fromthe steam-chest, to act upon the exterior periphery and bottom ofthe ring f, to make the saidA ring contract steam-tight around g and compressthe latter steam-tight around the inner face of the cavity c, and topress both rings up steam-tight against the inner face of the cover B,and vthereby exclude the steam entirely from the portion of the back ofthe valve inside ofthe ring q, the area ot' which is nearly equal tothat ot' the face of the valve.

An important feature of the invention consists in the employment of thesteam-pressure itself to keep the packing' tight and exclude the steamfrom the back of the valve.

I prefer to make the outer ring of the angular form represented in itstransverse section, but this form is not indispensable, as two or threeplain rings surrounding and fitting each other will serve to make asteam-tight joint.

Instead'of making the tlange d and projection d of circular form, it maybe made of the form of a parallelogram, corresponding with the formofthe face ofthe valve, and, instead of the ring-packing, packing of aform corresponding with the flange will then be used, the outer packing,which takes the place of the rin g j", being in four straight pieces,forming the four sides of the parallelogram, with `the joints at thecorners, and the inner packing, which takes the place of the ring g,being composed of four angle-pieces with the joints openings jj in suchmanner as to compress' or contract the packing around the inner face ofthe said cavity and at the same time press it against the cover or backof the steam-chest, all substantially as herein speeied.

WILLIAM B. ROBINSON.

Vitnesses JEFFERSON WILEY7 WM. WILEY.

